Most Unitarians would be surprised to learn that the first established Unitarian Churches were in Hungary, established mostly among the Szekely Hungarian population, a people with a long history of religious freedom and communitarian socio-economic relations. Indeed, that surprise comes from little knowledge of the history of Eastern Europe, at least during the first millennium of the Christian Era. Yet, the understanding of the roots and development of Unitarianism has much to do with that history, and with the Szekely people’s religious flowering during the last four decades of the 16th Century. Pre-9th Century Szekely history is in itself a complex one, due to many migrations with tribal regroupings, and varying patterns of rule or subjection, while tracing its record is aggravated by problems created by the sources, all foreign, written in a half dozen archaic languages, such as inaccuracies in locating and/or dating, differences in naming, and non-recognition of mere name changes. Consequently, professional Hungarian historians, of different disciplines, have arrived at different views on the origin both of the name Szekely and of the people themselves. This study deals with them in the first part, taking us to the Khazar experience, followed by the founding of the Hungarian nation and state under Szekely leadership. The second part deals with the introduction of Christianity, the establishment of the Christian Kingdom, with its Trinitarian belief system and feudal socio-economic relations, and the programmatic eradication of the non-Christian past, and with the ruling Arpad House’s centuries long struggle for acceptance of these changes, particularly with its kin, the Szekelys. Finally, the study brings us to the Hungarian martyr David Ference and the birth of Unitarianism in Hungarian Transylvania during the 16th Century Reformation. Dr. Ehrenthal presents us with an impressive manuscript, a well documented and referenced scholarly work, offering new historical interpretations that bring to life and make an invaluable contribution to the intimate relationship between Unitarian and Hungarian history.